A tour bus carrying gamblers to an Indian casino overturned along a Southern California freeway after sideswiping a car, injuring more than 50 people on board Thursday, authorities said.

A tour bus carrying gamblers to an Indian casino overturned along a Southern California freeway after sideswiping a car, injuring more than 50 people on board. (KTLA)

The driver made an "unsafe lane change" to the left, struck the car "and then overcorrected to the right," California Highway Patrol Officer Elizabeth Van Valkenburgh said. The skidding bus careened through a chain-link fence and down a dirt embankment, where it came to rest on its right side between the freeway and railroad tracks.

Ambulances and helicopters converged on Interstate 210 in Irwindale, about 20 miles east of downtown Los Angeles, where firefighters laid out red, yellow and green tarps to evaluate the injured.

Some of the passengers were able to get out on their own, while others needed to be rescued by firefighters or drivers who stopped to help, said Los Angeles County Fire Capt. Brian Jordan.

The bus driver was properly licensed and has not been charged, the CHP said. He was identified as Jinquan Yang, 55, of Alhambra.

A call to a phone listing for a Jinquan Yang in Alhambra went unanswered Thursday evening.

The driver whose car Yang struck was not injured.

Eight bus passengers needed immediate medical attention, including five who were flown by helicopter to Los Angeles County-USC Medical Center. The patients, who suffered blunt force trauma, were in guarded condition, said Dr. Leo Rodriguez.

Huntington Memorial Hospital in nearby Pasadena treated three people, including an 86-year-old man who had broken ribs. All were expected to survive, said hospital spokesman Kevin Andrus.

Many of the victims spoke only Mandarin or Cantonese and required translators.

The accident happened on a sunny day around 10 a.m. The freeway's eastbound lanes were at least partially closed for about six hours.

The bus was operated by Da Zhen Travel Agency in the Los Angeles suburb of Monterey Park. It was heading to the San Manuel Indian Bingo and Casino in Highland after picking up passengers in Monterey Park and San Gabriel, Van Valkenburgh said.

That large casino complex is about 40 miles east of the crash.

Da Zhen received a "satisfactory" rating during its last major review by federal inspectors, in 2010, according to U.S. Department of Transportation records.

Those records report that in the past two years, the company had no crashes among its nine buses. Two of its buses were cited for speeding in Arizona in February, while another was cited for "following too close" in May in Nevada.

Overall, the buses performed relatively well in mechanical inspections, failing just two of 30 over the past two years, according to the records. That 7 percent rate was significantly below the national average.

A schedule provided by the casino shows that Da Zhen runs 14 trips each day to San Manuel from various cities in Los Angeles County.

Interstate 210 is a commonly used foothill route to inland valleys and the desert east of Los Angeles. "Gamblers' specials" many catering to older people, frequently use it to bus tourists between the San Gabriel Valley and casinos in California and Las Vegas.